Motorhome 2 headset tubes glowing red

Second tubes back from the front, both sides. Do 460s in heavy duty use burn exhaust valves in those cylinders? About 1 minite after startup trying to run in new RV cam, ran it 5 min. and got scared, shut it down.
Thanks

If your timing is still at 0 you need to advance it some.

Carb or EFI??

Carb... I'll look for a vacuum leak that feeds those cylinders? Maybe a vacuum tee.
Don't think it's timming only 2 tubes glowing

Ive seen that happen when the valve isnt completely closing due to too much lifter preload causing the lifter to pump up and have the valve open a touch. was any machining done to the engine that could cause it to have to much lifter preload...?

Or a burnt exhaust valve could be the issue

Motor is a rebuild...not mine, 7k miles and ate two cam lobes ant the bottom of one lifter, had a slight clatter to it. Then it bent push rod and threw a lifter out of the bore, lost oil pressure. I r&r cam and lifters and on start up got the 2 glowing header tubes.

Oh it had long push rods in it...like 8.62, I figured that was done to get it off warranty! I put in stock 8.55, preload seemed right. I'm working on a class a with no front access...broke down in a dirt parking lot, mostly mud here in raining CA.

X2 on ignition timing. When breaking in camshaft we typically try to run 30 or more degrees timing while the cam is breaking in. In some cases while on dyno I have had to hook up the vacuum advance to cool the headers down. This even when air fuel ratios are in the high 13's akin to cruise mode. A factory carb will likely be even leaner.

Double check timing and for any potential vacuum leaks.

What is your initial timing set at? Total timing less vacuum advance?




S

Yes, next day I kicked timing ahead, cranked down intake bolts, ran her for 25 minutes to finish cam break in. Every thing looked good.

Since your initial startup only lasted 5 minutes, I would keep a close eye on the lifter preload. Typically cam break in should last 20- 30 minutes of continuous run time.